Cargo containers need to be inspected at ports and other points of entry or transportation for contraband such as explosives, narcotics, currency, chemical and nuclear weapons and for cargo-manifest verification. A cargo manifest is a physical or electronic shipping document that accompanies the cargo and provides important descriptive information about the cargo, including bills of lading issued by the carrier or its representative(s), the shipment's cosigner and/or consignee, cargo description, amount, value, origin, and/or destination. The accurate detection of contraband with a low false alarm is a daunting task, as these materials often have similar physical characteristics as benign cargo. The percentage of cargo to be inspected is increasing, and because of the currently manually intensive nature of inspections, so is the number of operators.
Security systems are thus limited in their ability to detect contraband, weapons, explosives, and other dangerous objects concealed in cargo. Standard and advanced X-ray systems have difficulty detecting contraband in break-bulk cargo. This difficulty is exacerbated when inspecting larger and oftentimes, cluttered pallets and cargo containers. Computed Tomography (CT) based systems have been shown to be more suitable for the difficult task of detecting aviation-threat explosives in luggage and, more recently, in larger objects. However, the configuration of commonly employed CT systems prevents scaling the system up to long objects such as large cargo containers and large skids.
The problem is further compounded by the fact that as a result of the image modulation according to atomic numbers of various materials, it is common for X-ray imaging systems to produce images with dark areas. Although these dark areas might indicate the presence of threat materials, they yield little information about the exact nature of threat. Also, radiographs produced by conventional X-ray systems are often difficult to interpret because objects are superimposed. Therefore, a trained operator must study and interpret each image to render an opinion on whether or not a target of interest, a threat, is present. Operator fatigue and distraction can compromise detection performance, especially when a large number of such radiographs is to be interpreted, such as at high traffic transit points and ports. Even with automated systems, it becomes difficult to comply with the implied requirement to keep the number of false alarms low, when the system is operated at high throughputs.
Therefore, there is a need to provide an automated detection system that further includes assistance tools to help operators improve their throughput by scrutinizing cargo images more efficiently, thereby increasing detection and analysis speed. There is also a need for such systems to operate with reduced false alarm rates.